Technical Field
The present invention relates to a magnetic element capable of transferring a skyrmion, a skyrmion memory using the magnetic element, a shift register using the magnetic element, a skyrmion memory device using the magnetic element, a skyrmion memory embedded solid-state electronic device, a data recording apparatus with a built-in skyrmion memory, a data processing apparatus with a built-in skyrmion memory, and a communication apparatus with a built-in skyrmion memory.
Related Art
A magnetic element is known that uses a magnetic moment of a magnet as digital information. The magnetic element has a nanoscale magnetic structure that functions as an element of a non-volatile memory that does not require electrical power when information is held. Based on advantages of ultrahigh density properties or the like from the nanoscale magnetic structure, the magnetic element is expected to be applied as a magnetic medium with large storage capacity of information, and the importance thereof increases as a memory device of an electronic device.
As a candidate for a next-generation magnetic memory device, a magnetic shift register has been proposed mainly by IBM in the United States. The magnetic shift register drives a magnetic domain wall, transfers an arrangement of the magnetic moment thereof through a current, and reads stored information (refer to Patent Document 1).
FIG. 29 is a schematic view showing the principle of driving of magnetic domain wall with current. The domain wall is a boundary of a magnetic region where the orientations of magnetic moments are mutually phase-inverted. In FIG. 29, the domain walls in a magnetic shift register 1 are shown by solid lines. The magnetic domain walls are driven by causing a current with the orientation of arrows to flow in the magnetic shift register 1. The magnetism by the orientation of the magnetic moments positioned above a magnetic sensor 2 changes by moving the domain wall. This magnetic change is sensed by the magnetic sensor 2, and magnetic information is derived.
However, this type of magnetic shift register 1 requires a large current when the magnetic domain walls are moved, and also has a drawback in that transfer velocity of the magnetic domain walls is low. As a result, writing time and erasing time of memory become slow, increasing power consumption.
Therefore, the inventors of the present application proposed a skyrmion magnetic element that uses skyrmions generated in the magnet as a storage unit (Patent Document 2). Further, in Non-Patent Document 1, the inventors of the present application showed that it is possible to transfer skyrmions in an arrangement in which the skyrmions are transferred substantially parallel to the direction of current.
In the present specification, the arrangement in which the drive current and the transfer direction of the skyrmions are substantially parallel is defined as a longitudinal transfer arrangement. In a case where the longitudinal transfer arrangement disclosed in Non-Patent Document 1 is applied as a memory, electrodes that apply current are provided to both end portions of the fine line structure of the magnet having skyrmions. Therefore, a width of the fine line is nanoscale, a resistance value between both end portions of the long fine line is large, and thus, it is not possible to cause a large current density to flow. Therefore, there is a restriction on current density for the current, and the transfer velocity of the skyrmion becomes low. There is a problem in that memory writing time and memory reading time are not shortened. Non-Patent Document 1 proposes skyrmion transfer by steady-state current as a storage memory. Since the steady-state current is necessary, the skyrmion transfer cannot be used as a non-volatile memory. Also, since Non-Patent Document 1 does not disclose a method of achieving a memory function when the skyrmion transfer is applied as a memory, there is a major problem in putting it into practical use.